Davis Open Mapping Party

Yesterday I got an email announcement about a Davis OpenStreetMap mapping party to be held today. The OpenStreetMap project is one of these collaborative open data projects that I’ve known about for some time, but haven’t really dived into it, so I was glad to have the introduction to it today. The impetus behind this project is that there is very little street map data in this world that is free in the sense of being legally unencumbered, allowing one to make full creative use of it. The online mapping services provided by Google Maps and Mapquest are good examples of not free-as-in-speech data, but so is map data from most government mapping agencies, e.g. the Ordnance Survey. (The United States is an exception here, since federally-produced mapping data is in the public domain.)

Since everybody and their dog now has a GPS unit, some enterprising geeks came up with the idea to start mapping the world’s streets with their GPSs and make all the collected map data freely available for any use. Thus was born the OpenStreetMap project, which has really taken off in the almost four years it has been underway. As of June 2008 there are over 22 million kilometers of highways and byways mapped in the system, and over 32,000 registered users who are able to add to and update the map, which is essentially a cartographic wiki.

For some reason the project’s founder, Steve Coast, was in town today so a few of us gathered together at the café Delta of Venus at 10 AM to plan our mapping session. Thanks to the public domain TIGER data provided by the U.S. Census Bureau, there is good street mapping for most places in the United States, including Davis, already uploaded into the OpenStreetMap, but there are always details to fill in — no maps are ever finished. We decided to work on bike paths and other paths. I opted to head up to the North Davis Greenbelt and collect GPS tracks for every bit of the bike paths there, including the connectors to all the side streets. There is already some mapping of these bike paths in the OpenStreetMap, but there are definitely bits to add.

It was a very hot day today (up to 102° F) and I was glad to return to Delta of Venus for lunch at 1:30 PM. There I got some exposure to the map editing tools but have yet to download the track data off my GPS, let alone start the process of editing the map online.

It’s a great project. There are lots of technical details to learn, much of which are of substantial cartographic interest (e.g. how do you classify the features you’re trying to map), and all completely fascinating from a geographer’s point of view.